:root {
  --bg: #081420;
  --panel-border: #2c4864;
  --text: #f3f7fa;
  --muted: #9eb2c4;
  --radius: 16px;
  --accent: #53e3c2;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: "IBM Plex Sans", sans-serif;
  color: var(--text);
  background: var(--bg);
}

.bg-layer {
  position: fixed;
  inset: 0;
  z-index: -1;
  background:
    radial-gradient(circle at 8% 15%, #164667 0%, transparent 36%),
    radial-gradient(circle at 78% 12%, #3d2c5f 0%, transparent 30%),
    radial-gradient(circle at 26% 92%, #1b4d45 0%, transparent 32%),
    linear-gradient(145deg, #07111b 0%, #0f2235 55%, #091523 100%);
}

h1,
h2,
h3,
h4,
summary {
  font-family: "Space Grotesk", sans-serif;
}

.topbar {
  max-width: 1400px;
  margin: 0 auto;
  padding: 22px 20px 10px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 10px;
}

.topbar h1 {
  margin: 0;
  font-size: clamp(1.4rem, 3vw, 2rem);
}

.brand-line {
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.brand-subtitle {
  margin: 0;
  color: var(--muted);
  font-size: 0.9rem;
  font-weight: 500;
}

.top-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.github-icon-link {
  width: 34px;
  height: 34px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  border: 1px solid rgb(67 101 131 / 78%);
  border-radius: 10px;
  background: rgb(15 33 49 / 72%);
  color: #b7c8d8;
  text-decoration: none;
  transition: background 130ms ease, border-color 130ms ease, color 130ms ease, transform 130ms ease;
}

.github-icon-link svg {
  width: 16px;
  height: 16px;
  fill: currentColor;
}

.github-icon-link:hover,
.github-icon-link:focus-visible {
  background: rgb(25 50 73 / 82%);
  border-color: rgb(98 132 166 / 88%);
  color: #dbe9f7;
  transform: translateY(-1px);
}

.container {
  max-width: 1400px;
  margin: 0 auto;
  padding: 10px 20px 28px;
}

.controls {
  border: 1px solid var(--panel-border);
  border-radius: var(--radius);
  background: rgb(11 24 37 / 92%);
  padding: 14px;
  display: grid;
  grid-template-columns: minmax(240px, 1fr) auto auto;
  gap: 10px;
  align-items: end;
  margin-bottom: 14px;
}

.controls label {
  display: flex;
  flex-direction: column;
  gap: 6px;
  color: var(--muted);
  font-size: 0.9rem;
}

input {
  border: 1px solid var(--panel-border);
  border-radius: 11px;
  background: #0a1726;
  color: var(--text);
  padding: 9px 12px;
  font: inherit;
}

.actions {
  display: flex;
  gap: 8px;
}

button,
.page-link {
  border: 1px solid #41729f;
  border-radius: 10px;
  background: #1a3551;
  color: #e9f4ff;
  text-decoration: none;
  padding: 8px 12px;
  font-size: 0.86rem;
  font-weight: 600;
  cursor: pointer;
}

button:hover,
button:focus,
.page-link:hover,
.page-link:focus {
  background: #23466a;
}

.count {
  margin: 0;
  color: var(--muted);
  font-size: 0.9rem;
}

.mindmap-tree {
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.node {
  border: 1px solid var(--panel-border);
  border-radius: 14px;
  background: rgb(12 28 44 / 85%);
  padding: 9px;
}

.node > summary {
  list-style: none;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 10px;
  font-size: 1rem;
}

.node > summary::-webkit-details-marker {
  display: none;
}

.node > summary::before {
  content: "+";
  color: var(--accent);
  font-weight: 700;
  margin-right: 8px;
}

.node[open] > summary::before {
  content: "-";
}

.count-pill {
  border: 1px solid var(--panel-border);
  border-radius: 999px;
  color: var(--muted);
  font-size: 0.8rem;
  padding: 3px 8px;
}

.node-children {
  margin-top: 9px;
  padding-left: 14px;
  border-left: 2px solid rgb(65 110 152 / 55%);
  display: flex;
  flex-direction: column;
  gap: 9px;
}

.sub-node {
  border: 1px solid rgb(49 80 108 / 80%);
  border-radius: 10px;
  background: rgb(7 21 33 / 86%);
  padding: 8px;
}

.sub-node > summary {
  list-style: none;
  cursor: pointer;
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: 0.9rem;
  color: #e8f2ff;
}

.sub-node > summary::-webkit-details-marker {
  display: none;
}

.sub-node > summary::before {
  content: ">";
  color: #8ecbff;
  margin-right: 8px;
}

.sub-node[open] > summary::before {
  content: "v";
}

.leaf-grid {
  margin-top: 8px;
  display: flex;
  flex-wrap: wrap;
  gap: 7px;
}

.leaf {
  position: relative;
  border: 1px solid #3a6692;
  background: #24496e;
  color: #f1f8ff;
  text-decoration: none;
  border-radius: 8px;
  font-size: 0.78rem;
  line-height: 1;
  padding: 5px 8px;
}

.leaf::after {
  content: attr(data-tooltip);
  position: absolute;
  left: 0;
  bottom: calc(100% + 8px);
  min-width: 220px;
  max-width: 340px;
  border: 1px solid #5f7ca0;
  border-radius: 10px;
  background: #1e3d63;
  color: #f5fbff;
  padding: 8px 10px;
  line-height: 1.25;
  white-space: pre-line;
  pointer-events: none;
  opacity: 0;
  transform: translateY(3px);
  transition: opacity 120ms ease, transform 120ms ease;
  z-index: 40;
}

.leaf:hover::after,
.leaf:focus-visible::after {
  opacity: 1;
  transform: translateY(0);
}

.leaf.hidden {
  display: none;
}

.leaf.level-expert {
  border-color: #934541;
  background: #aa514a;
}

.leaf.level-advanced {
  border-color: #3f588f;
  background: #2f4f80;
}

.leaf.level-intermediate {
  border-color: #2f7c63;
  background: #266753;
}

.leaf.level-foundational {
  border-color: #706023;
  background: #6d5921;
}

.leaf.ai {
  box-shadow: 0 0 0 1px #2ec7a4 inset;
}

@media (max-width: 900px) {
  .controls {
    grid-template-columns: 1fr;
  }

  .actions {
    justify-content: flex-start;
  }
}